13 November 2023

The reroof of St Andrew’s Church with Welsh Slate wins AC Nurden an award shortlisting.

Every cloud has a silver lining, they say. And so it seems above St Andrew’s Church in Wanborough, Wiltshire, where the lead roof that was stolen has been replaced with Welsh Slate in a project that has won a shortlisting in some national awards.

The scheme by specialist contractors AC Nurden, using Welsh Slate’s 7mm-thick 500mm x 250mm Cwt-Y-Bugail Dark Blue Grey slates, is through to the finals in the “Best use of a heritage roof” category in the 2023 Pitched Roofing Awards which will be announced on 24 November.

Largely rebuilt in the early 14th Century with rubble and stone slate roofs, the church is an important landmark with a distinctive (and rare) arrangement of two separate towers – the eastern one with a spire – and has been a place of worship for the village for 900 years. It not only lies within Wanborough (Upper) Conservation Area but also sits within the North Wessex Downs Area of Outstanding Natural Beauty.

Almost a year to the day, AC Nurden director Andy Nurden received a call from a church warden at Lyddington and Wanborough Parochial Church Council as their Grade I listed church had fallen prey to thieves who had stolen all the lead from the south side of the upper nave roof as well as a large section from the north facing slope.

There was also considerable damage to the walls and gutters, and subsequent rain had soaked the pews, carpet and kneelers inside the church. Even the graveyard had been damaged where a large section of lead and tools had fallen and been left behind, indicating the thieves may have been disturbed.

In the weeks after, the entire community rallied around fundraising efforts and collected a sufficient sum to begin the roof repairs.

These included overlaying the remains of the existing roof with oak rafters to raise the level of the nave roof by 100mm to ensure an adequate step into the parapet gutters. The roof had been lowered in the 15th Century (and the nave walls raised) to form a clerestory but capillary action meant rainwater was seeping through this junction.

This meant the pitch of the roof was shallower (approximately 25-30°) which required the head lap/gauge of the slates to be increased from the usual 50mm to 65-70mm. AC Nurden had to drill the fixing holes in a different position due to this.

Andy Nurden said: ““The good thing is we can still get good quality Welsh Slate and the quality coming through is really good. Where you get some of the imitation slates, they just look false.

“I like that it is something local to us, that it has been dug out of the ground, and that it is nice to work with. It really does look beautiful. And the people we have been dealing with at Welsh Slate have been brilliant.”

He added: “The Welsh Slate combined with the oak ensured that the finished project was not only ethical but also preserved the rich heritage and aesthetic value of St Andrew’s Church and Wanborough parish.

“The job was completed on time and within budget despite inclement weather early on. The PCC were extremely happy with the finished product and the service provided and have since been back in touch to book more repair work.”

AC Nurden are a third-generation roofing and building company specialising in luxury new-build homes and barn conversions using a complementary mix of Welsh Slate for the roofs and Cotswold stone for the facades/roofs. They used a roofing apprentice on St Andrew’s – the son of a master roofer who has been with them for more than 20 years.

The AC Nurden team also had to ensure that the inside of the church was safe for the congregation who still needed to use the building during construction. Residents of the parish and visitors were understandably upset by the theft, and AC Nurden staff often needed to offer support and words of kindness while their place of worship was closed to the public.

Prior to the works, a Heritage Impact Statement (HIS) was prepared by Andrew Townsend Architects (ATA), historic buildings consultants who, as inspecting architects, have assisted the PCC with the care of St Andrew’s for more than 30 years. ATA also prepared the specification for the works, assisted with applications for planning consent and faculty permission as well as administering the contract on behalf of the PCC.

The HIS said: “The proposed works arose as a result of theft of most of the existing lead sheet covering from the nave roof. As part of consideration of the feasibility of the various options, [ATA] provided an outline schedule with budget cost estimates showing three possibilities for re-roofing the nave - lead sheet, terne-coated stainless steel sheet, and Welsh Slate. Following discussions between members of the PCC about the options, [ATA] were directed to investigate the possibility of gaining faculty and planning consents for re-roofing the nave in Welsh Slate.

“The standard, time-tested approach – advocated by Historic England, the Society for the Protection of Ancient Buildings and others – to the repair of historic structures is to carry out essential repair work on a like-for-like basis. So, in normal circumstances, lead sheet would have been considered the best material to use in the renewal of the nave roof at St Andrew’s. However, the PCC expressed a concern about this for the following reasons:

1) There is a recent history of lead being stolen from the nave roof. On the last occasion, approximately two-thirds of the lead sheet was stripped. On the two previous occasions, in the 1990s and 2015, a few bays were removed each time.

2) Insurance cover is available only for a relatively small proportion of the cost of replacement of a lead roof.

3) Wanborough PCC is not a wealthy body - providing funding for the current proposals will empty their coffers as well as requiring a major appeal to villagers and external grant-giving bodies.

4) The current cost of re-roofing the nave in lead sheet is considerably greater than the alternatives considered below (approximately £25,000 + VAT).

5) The funding climate for repairs to CofE places of worship has become more precarious in recent years following the cessation of Historic England/English Heritage/National Lottery Heritage Fund grant schemes for the repair of places of worship.

“Where a rationale for the replacement of lead sheet has been established, HE advice indicates a preference for replacement using terne-coated stainless steel - a sheet metal with a coating of tin which dulls the usual shiny appearance of stainless steel to a grey. It can be laid using jointing details broadly imitating those of leadwork, is thought to be durable and has low attraction for theft due to the difficulty of removal and low scrap value.

“On the negative side, it is often difficult to detail elegantly and has a hard/rigid/crisp appearance which feels much less sympathetic than leadwork in locations on many historic buildings. Noise created by heavy rainfall is likely to be distracting for the church congregation, particularly as the roof is over the nave where the majority of people sit. There may also be philosophical questions about the use of one material (stainless steel) being used to imitate another (lead sheet). Although there are some precedents for this, this tends to be a rare trait in ancient parish churches where on the whole there is a simple ‘honesty’ of construction methods and materials.

“As the nave roof has an existing pitch of above 20 ̊, the alternative of Welsh slate can be considered. The benefits of using this material in preference to terne-coated stainless steel and other sheet metals are as follows:

  • Welsh slate is quarried in the UK.
  • Wanborough is located near Swindon where the local vernacular, since the arrival of the railways, has included the extensive use of Welsh Slate - a number of the older buildings in Upper Wanborough are roofed in Welsh Slate.
  • A Welsh slate roof is relatively easy to repair – slipped/damaged slates can be simply replaced but if terne-coated stainless steel is damaged or is leaking, repair is more difficult.
  • Detailing of junctions between a Welsh Slate roof and e.g., masonry parapets/upstands is often more straightforward than for terne-coated stainless steel.
  • A Welsh Slate roof is just what it is and is not attempting to imitate another material.
  • The appearance of a Welsh Slate roof and the way it weathers may be considered to work well in the context of a historic building such as Wanborough church whereas the hard/crisp lines of terne-coated stainless steel feel less appropriate in this context.
  • The cost of a new Welsh slate roof covering is roughly comparable with terne-coated stainless steel.

Andrew Townsend concluded: “This case demonstrates that, where there is a threat of repeated theft of lead sheet roofing, Welsh Slate can be used successfully in its place instead of the increasingly ubiquitous (and, in my opinion, unsympathetic) terne-coated stainless steel.”


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